Image forming apparatus for normal and thick print media

Abstract

An image-forming apparatus includes a developing roller and a developing blade. The developing blade applies toner to the developing roller to form a thin layer of toner on the developing roller. The image-forming apparatus performs a printing operation that includes a paper-feeding period and a developing period following the paper-feeding period. The developing roller rotates relative to the developing blade at a first speed during the paper-feeding period and then at a lower second speed than during the developing period, thereby eliminating chance of white lines of occurring in a printed image. The developing roller may be rotated at a constant speed in each printing operation until the circumferential surface of the developing roller has traveled over a certain cumulative distance. When the surface has traveled over the first distance, the developing roller may be rotated at an increased speed over a certain distance.

What is claimed is:  
     
       1. An image-forming apparatus comprising: 
       a developing member, rotating in contact with a photoconductor to deposit toner to an electrostatic latent image formed on the photoconductor; and  
       a toner applying member, applying toner to said developing member, said toner applying member forming a thin layer of toner on said developing member;  
       wherein the image-forming apparatus performs a printing operation that includes a first period and a second period following the first period, and said developing member rotates relative to said toner applying member at a first circumferential speed during the first period and then at a second circumferential speed lower than the first circumferential speed during the second period.  
     
     
       2. The image-forming apparatus according to  claim 1 , wherein the first period is a length of time during which a print medium is fed to a predetermined position from a medium-holding cassette, 
       wherein the second period is a length of time during which the toner is deposited to the electrostatic latent image.  
     
     
       3. The image-forming apparatus according to  claim 1 , wherein the first circumferential speed is between 73 mm/s and 1015 mm/s. 
     
     
       4. The image-forming apparatus according to  claim 1 , wherein the second circumferential speed is lower than 73 mm/s. 
     
     
       5. An image-forming apparatus comprising: 
       a developing member, rotating in contact with a photoconductor to deposit toner to an electrostatic latent image formed on the photoconductor; and  
       a toner applying member, applying toner to said developing member, said toner applying member forming a thin layer of toner on said developing member;  
       wherein said developing member rotates relative to said toner applying member at a first circumferential speed until a surface of said developing member has traveled over a first cumulative circumferential distance with respect to said toner applying member; and  
       wherein if the surface has traveled over the first cumulative circumferential distance, then said developing member rotates relative to said toner applying member at a second circumferential speed over a second circumferential distance after a developing operation of a page of medium, the second circumferential speed being higher than the first circumferential speed.  
     
     
       6. The image-forming apparatus according to  claim 5 , wherein the first circumferential distance is shorter than a distance such that print quality begins to be deteriorated. 
     
     
       7. The image-forming apparatus according to  claim 5 , wherein the first circumferential speed is lower than 73 mm/s. 
     
     
       8. The image-forming apparatus according to  claim 5 , wherein the second circumferential speed is between 73 mm/s and 1015 mm/s. 
     
     
       9. The image-forming apparatus according to  claim 5 , wherein the second circumferential distance is longer than half a nip formed between said developing member and said toner applying member. 
     
     
       10. The image-forming apparatus according to  claim 5 , wherein the first cumulative circumferential distance is less than 456,960 mm. 
     
     
       11. The image-forming apparatus according to  claim 5 , wherein after said developing member has rotated at the second circumferential speed over the second circumferential distance, said developing member rotates at the first circumferential speed with respect to said toner applying member to perform another developing operation. 
     
     
       12. The image-forming apparatus according to  claim 5 , wherein after the image-forming apparatus becomes ready to the developing operation at the first circumferential speed, a counting operation is initiated to count a cumulative circumferential distance over which said developing member rotates at the first circumferential speed. 
     
     
       13. The image-forming apparatus according to  claim 5 , wherein when the developing operation is carried out on a predetermined medium, said developing member rotates at the first circumferential speed. 
     
     
       14. An image-forming apparatus comprising: 
       a developing member, rotating to deposit toner to an electrostatic latent image formed on a photoconductor; and  
       a toner applying member, applying toner to said developing member in pressure contact with said developing member to form a thin layer of toner on said developing member;  
       wherein when a developing operation is not being carried out on a print medium, said developing member rotates over a first circumferential distance at a at a first circumferential speed; and  
       wherein when the developing operation is being carried out on the print medium, said developing member rotates at a second circumferential speed lower than the first circumferential speed.  
     
     
       15. The image-forming apparatus according to  claim 14 , wherein the print medium undergoes an operation before it undergoes the developing operation. 
     
     
       16. The image-forming apparatus according to  claim 15 , wherein the operation before the medium undergoes the developing operation is a medium-feeding operation operation. 
     
     
       17. The image-forming apparatus according to  claim 14 , wherein the print medium undergoes a first operation and then a second operation which is a developing operation. 
     
     
       18. The image-forming apparatus according to  claim 17 , wherein the first operation is a medium-feeding operation operation. 
     
     
       19. The image-forming apparatus according to  claim 14 , wherein the first circumferential distance is at least half a nip formed between said developing member and said toner applying member. 
     
     
       20. The image-forming apparatus according to  claim 14 , wherein when the developing operation is carried out on a predetermined medium to form a permanent image on the medium, said developing member rotates at the second circumferential speed.